Microchemist&#39;s syringe



July 17, 1951 c. H.4 HAMILTON MICROCHEMIST'S SYRINGE Filed Deo. 21, 1949 FIE 1 FIE E INVENTOR. /a/f H Hemi/fon fro/mw Patented July 17, 1951 UNITED STATESPATENT OFFICE MICROCHEMISTS SYRINGE Clark H. Hamilton, Oakland, Calif.

Application December 21, 1949, Serial No. 134,240

(Cl. 7S-425.6)

Claims.

My invention relates to means useful in connection with the work of a microchemist to assist him in measuring relatively minute quantities of materials in an accurate and reproduceable way.

In microchemistry and particularly in handling radio active materials, it is necessary to provide a means for measuring small volumes of material. The volumes are of the order of one lambda in magnitude, one lambda being a millionth of a liter. It is often necessary for the microchemist to manipulate his equipment inside of a hood provided with rubber gloves, so that he is not irradiated. Manipulation of equipment by use of gloves and within a hood is diicult at best and in operating a micromeasure to obtain accuracy under these conditions is a severe chore.

It is therefore an object of my invention to provide a microchemists syringe effective for accurate operation by the chemist even while gloved or operating in a gloved hood.

A further object of the invention is to provide a microchemists syringe effective to meter quantities of material accurately and reproduceably.

Another object of the invention is to provide a microchemists syringe readily operable with one hand.

Another object of the invention is to provide a microchemists syringe simple to manufacture, to clean, and to handle.

Another object of the invention is to provide a microchemists syringe of a relatively inexpensive construction.

A still further object of the invention is to provide a microchemists syringe which is in general an improvement over syringes now available.

Other objects together with the foregoing are attained in the forms of my invention described in the accompanying description and illustrated in the drawings in which v Figure 1 is a cross section on a longitudinal axial pla-ne through one form of microchemists syringe in accordance with my invention.

Figure 2 is a cross section on a longitudinal axial plane through a modified form of microchemists syringe of my invention.

While variations in the particular form of my invention can be made depending upon the environment in which it is to be principally utilized and depending somewhat upon the preferences and facilities of an individual user, it has successfully been embodied in the forms illustrated herein. In the arrangement shown particularly in Figure 1, I provide a generally tubular body 6 of glass or other comparable, inert ma- .a smooth, circular-cylindrical bore l.

terial formed throughout most of its length with At its lower end, the body is diminished in cross section to provide an external taper 8 adapted to intert with any standard pipette; for example, a one lambda pipette, and to provide an internal passage 9 merging with the interior bore l. At its other end, the body 6 is provided with a reinforcing lip I I or flange affording a convenient point for grasping by the user and affording an abutment for his thumb or ngers.

Disposed within the bore 1 is a circular-cylindrical sleeve I2 preferably formed of stainless steel or comparable inert material and circularcylindrical in cross section to provide a smooth exterior surface I3. The surface I3 very carefully fits the bore 'l so that the sleeve I2 is slidable within the body 6 and is also rotatable in the body.

The interior of the sleeve I2, especially adjacent its inner or lower end is formed with threads I4 of the customary helical kind. A similar group of threads 16 at the lower end of a plunger Il engages these threads. By this threaded engagement, the plunger I1 is rotatable and axially movable within and with respect to the sleeve I2. A stem I8 extends from the plunger Il through the sleeve I2 and emerges from one end thereof in an extension I9. A suitable bushing 2l or bearing is disposed between the sleeve I2 and the stem I8 as an additional support and guide. On its extended end I9 the stem I8 carries a thumb wheel 22 held in place by a set screw 23 so that thumb wheel and the stem I9 as well as the plunger Il rotate in unison.

It is a characteristic of my microchemists syringe that the friction of turning the plunger Il within the sleeve I2 to produce axial translation or motion of the plunger is less than the rotational resistance between the sleeve I2 and the interior of the body 6. This is accomplished in any of several ways, partly by carefully coordinating the relative t between the sleeve I 2 and the bore 'I and the t between the plunger threads I6 and the internal threads I4 in the sleeve I2. The friction is also a function of the lubrication, if any, between these relatively moving surfaces and I particularly provide that the lubricant, if used, between the sleeve I2 and the body 6 is somewhat heavier or more resistant to rotation than the lubricant between the plunger Il and the sleeve I 2.

In the use of the structure a pipette is attached to the extension 8. The microchemist then grasps the body B with his little and ring fingers and utilizing his thumb and forenger against the wheel 22 and in part resting upon the rim Il, withdraws the sleeve l2 axially from the body 6 in a small amount to induce some air to ow into the pipette. After immersing the pipette, he then withdraws the sleeve l2 farther utilizing a similar finger and thumb movement until material drawn into -the pipette isnearly at a graduation mark.vr He then stops the axial movement of the thumb wheel 22 and rotates it. The resistance to turning between the sleeve I2 and the body 6 is sufficiently greater than the resistance to turning between the plungerl1land-'the sleeve l2 that the plunger rotates- Theplunger is withdrawn a very slight distance farther while the sleeve I2 remains in positiorr due to the-greater friction between the sleeve and the body 6 not only against rotational turning but also against any further axial withdrawal. In this way even though he is working with rubber gloves and at a distance in a hood the microchemist can accurately meter .the contents of the pipette. The contents of the pipette, after coming exactly to the graduation, are expelledl bysimple axial depression ofthe thumb wheel 22.

In a comparable fashion the microchemists syringe of Figure 2 is constructed to have a body 35 'with a circular-cylindrical, smooth, interior bore 31 merging with apassage 38 for connection to or communication witha pipette. The body 35 at its upper endhas an enlarged ilange 33. Within the body a sleeve 40 isrdisposed. The external surfacev 4l of vthe sleeve'ts within the'bore 31 of the body 35 with a predetermined amount of friction against rotation and axial translation. 'Ihe upper end'ot the sleeve 4Q' is provided with an enlarged 'linger member 43 carrying a bushing 44 within which a stem 46 is freely mounted., A thumb wheel 41 at the upper end of the stem is secured lin place by a set screw 48 and impartsV the movement of the thumb wheel to the stem. The lower end of the stem carries a threaded portionl 5lV engaging internal threads 52 on a plunger plug 53 located within and secured to the sleeve 40, preferably by cement. The relative friction between the threads on the plug 53 and the stem 46 and between the'sleeve 40 and the body 35 is such that rotation of the thumb wheel 41 produces-rotation of the stem and of the threaded portion 5| but produces only an axial translation of the plug 53 and the sleeve 40 within 4the body. The rotation of the wheel 41 does not produceany rotation of the plug 53 and thesleevel .within the body 36. 'I'he general operation of this form of structure is identical withthat shown in Figure l.

In both of these modifications, there is provided a microchemists syringe very simply made and very simply caredr for, fabricated of inexpensive materials andof inexpensive design. It is effective, for use in microchemistry -even when the microchemist is encumbered by gloves and by the necessity of working within a hood. It

4 i provides, in conjunction with standard pipette equipment, a means for measuring accurately and reproduceably minute quantities of chemical materials.

I claim:

1. A microchemists syringe comprising a body having a smooth circular-cylindrical bore merging with an outlet passage, a circular-cylindrical externally smooth sleeve lslidably disposed within said bore, said sleeve having internal threads, a plunger having threads engaging said internal threads, a stem on said plunger having one end extending beyond said sleeve, and a thumb wheel on the said end of the plunger.

2. A microchemists syringe comprising a tubular body having a smooth circular bore, an externally smooth circular sleeve slidably disposed within said bore, said sleeve having internal threads, a plunger having threads engaging said internal threads, and means for turning said plunger with respect to said sleeve.

3. A microchemists syringe comprising a tubular body having a smooth circular bore, an externally smooth circular sleeve slidably disposed 'within said bore and having a predetermined amount of frictional resistance to turning therein, said sleeve having internal threads, a plunger having threads engaging said internal threads and having a frictional resistance to turning therein less than said predetermined amount, and means for turning said plunger with respect to said sleeve.

4'. A microchemists syringe comprisingla body having a smooth circular bore, an externally smooth circular sleeve disposed within said bore inv sliding engagement with said'body, said sleeve having internal threads, and a plunger having threads engaging said internal threads, said plunger turning `in said sleeve easier than said sleeve turns insaid body.

5. A znicrochemists syringe comprisinga body having a circular-cylindrical smooth bore merging with an outlet passage, a circular-cylindrical externally smooth sleeve disposed within said borein sliding engagement with said'body, said sleeve having internal threads, a plunger having threads engaging said internal threads, said plunger "turning in said sleeve easier than said sleeve turns in said body, a'stem on said plunger having one end extending beyond said sleeve, and a thumb wheel on said end of the plunger.

CLARK I-l. HAMILTON.

REFERENCES CITED The following references are of record in the lile of this patent:

UNITED STATES PATENTS Number Name Date 1,433,075 Gottlieb Oct. 24, 1922 2,335,049 Finkelstein Nov. 23, 1943 FOREIGN PATENTS Number Country Date 239,388 Great Britain Sept. 10, 1925 

